It's worth noting that one of the reasons we never got space-based missile defense was that it was only recently that we've finally gotten launch costs down sufficiently to make it financially feasible, due to an almost demented policy failure for the past three decades. [1/n] https://t.co/ouaaIS9eUk

The first serious proposal for space-based missile defense was Lowell Wood's concept of "Brilliant Pebbles": Kinetic interceptors in orbit. But in order to implement it, launch costs had to be reduced far below those of the Shuttle and conventional USAF expendables.

The purpose of the DARPA DC-X program was to demonstrate the potential for reusable Single-Stage-To-Orbit, which many viewed as a requirement for low launch cost (SpaceX has since proven this to be mistaken).

DC-X did demonstrate vertical take-off and landing of single vehicle in an atmosphere (the Apollo LEM was two stage in a vacuum). It also demonstrated relatively rapid turnaround of a LOX/LH2 propulsion system. But then NASA took it over.

Another thing that the DC-X program demonstrated before its demise was that traditional cost models for new concepts were utter crap. SpaceX has since validated that. NAFCON cost model has been shown to be worse than worthless for non-traditional activities.

One of the biggest launch-policy errors of the 90s was to confine the military to expendables, and assign reusable space transports to NASA. It was nothing short of disastrous, setting us back over a decade.

After the X-33 debacle, which no one saw coming except anyone who understood how to do X programs, the idiotic lesson (fallacy of hasty generalization) drawn from it by NASA was that reusable launch systems weren't practical. Tell it to SpaceX.

X-33 should never have been awarded to Lockmart (their proposal wasn't compliant, in that the business plan was nonsense, but no one at MSFC would recognize a business plan if it kicked them in the ass). Also, should never have been a single award.

A key rule of X programs is that a vehicle only tests one new technology, on a platform that is otherwise well understood. VentureStar was testing single-stage to Montana, with a linear aerospike engine, and a conformal composite hydrogen tank. Huge and obvious tech risk.

X-33 was an example of NASA's Wile E. Coyote approach to technology development: Try some crazy thing, then when it doesn't work, don't try to figure out why and improve it, just assume it can't be done and go on to the next crazy thing.

And so we entered the 21st century with no one, neither USAF or NASA, even attempting to get launch costs down. Former was focused on mission assurance of expendable EELVs, and latter had devolved into a jobs program for giant expendable rockets.

But now, having done that, it's useful to go back and re-examine concepts for space-based missile defense that were financially infeasible with traditional launch costs of many thousands of dollars per pound. Cubesats are also a game changer.

More thoughts from John Wenz. This statement isn’t inaccurate, but it is a little misleading:

It was the first time humanity had orbited another body that wasn’t our home planet.

Yes, it was, but some have concluded from that fact that they weren’t orbiting earth. None of the Apollo missions left earth orbit, because they never reached escape velocity, and when you orbit a moon that is in orbit around a planet, you remain in orbit around that planet along with it. No human has ever left earth orbit, but Elon seems to have the most serious plans to do so.

One other point, unrelated to Wentz’s piece. I was looking at the Wikipedia page for the mission, and found this bit of (misleading, at best) history:

On August 9, 1968, Low discussed the idea with Gilruth, Flight Director Chris Kraft, and the Director of Flight Crew Operations, Donald Slayton. They then flew to the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, where they met with KSC Director Kurt Debus, Apollo Program Director Samuel C. Phillips, Rocco Petrone, and Wernher von Braun. Kraft considered the proposal feasible from a flight control standpoint; Debus and Petrone agreed that the next Saturn V, AS-503, could be made ready by December 1; and von Braun was confident that the pogo oscillation problems that had afflicted Apollo 6 had been fixed. Almost every senior manager at NASA agreed with this new mission, citing confidence in both the hardware and the personnel, along with the potential for a circumlunar flight providing a significant morale boost. The only person who needed some convincing was James E. Webb, the NASA administrator. Backed by the full support of his agency, Webb authorized the mission. Apollo 8 was officially changed from a “D” mission to a “C-Prime” lunar-orbit mission.

Webb may have authorized it in August, in the sense of changing the mission category, but this was probably to keep the option open, not because he supported doing it. I’m pretty sure he continued to oppose it, and it may be that one of the reasons for his retirement in October was to not have it happen on his watch (though he probably would have left anyway in the New Year, with the incoming administration of Nixon). Tom Paine (who did favor it), as Acting Administrator, actually made final approval in November, a few weeks before the flight.

Jeff Foust writes about the unheralded 25th anniversary of the DC-X flights, and what has happened in the past half decade to see the promise that it offered a quarter of a century ago finally coming to fruition. I attended the 20th anniversary, but the only thing happening this year is a dinner in LA later this month.

I would note, per the criticism of the “purists,” that SSTO is highly overrated. Two-stage systems are much more flexible and efficient, particularly for off-nominal missions (e.g., high inclination or high altitude). SSTO would make sense only for a large traffic model to a single destination, probably equatorial.

I’m going to reserve judgment until I see the film. I think that the proximate cause of the uproar wasn’t the decision to leave out the flag planting, but the Canadian actor’s idiotic explanation of it. As I note in comments, the movie is a biopick of Neil Armstrong, not a history of Apollo, and his great achievement was not in planting a flag on the moon, but in simply being present on its surface.